System for monitoring propane or other consumable liquid in remotely located storage tanks

ABSTRACT

An improved apparatus and method for monitoring the levels of propane or other consumable liquid in remotely located storage tanks and coordinating delivery of liquid to those tanks, including an improved method of using the remote monitoring data to identify out-of-ordinary conditions at remote tanks, optimally schedule purchases or deliveries, improve safety, and more efficiently operate a propane dealership. More accurate and timely information concerning the status of customer tanks serves to improve operational efficiencies and increase safety. Data received from remote sensors can be collected and organized so that it is easily understood and utilized through the implementation of a user interface accessible via the Internet that allows the information to be presented in an efficient graphical and contextual fashion. Operational efficiencies can also be improved by calculating site-specific Degree-days and K-factors for each tank and by taking historical propane usage for each tank, weather conditions, and projected fuel usage into account.

This application is a continuation of U.S. Non Provisional applicationSer. No. 13/086,641, filed on Apr. 14, 2011, which is a continuation ofU.S. Non Provisional application Ser. No. 12/777,055, filed May 10,2010, now U.S. Pat. No. 7,937,216, which is a Continuation-in-part ofU.S. Non Provisional application Ser. No. 12/363,502, filed Jan. 30,2009, now U.S. Pat. No. 7,937,215, which is a continuation of U.S. NonProvisional application Ser. No. 11/874,784, filed Oct. 18, 2007, nowU.S. Pat. No. 7,512,488, which is a continuation of U.S. Non Provisionalapplication Ser. No. 11/396,048, filed Mar. 31, 2006, which claimspriority from U.S. Provisional Application No. 60/683,465, filed May 20,2005, and claims priority from U.S. Provisional Application No.60/668,211, filed Apr. 2, 2005, which is a continuation of U.S. NonProvisional application Ser. No. 11/097,964, filed Apr. 1, 2005, nowU.S. Pat. No. 7,295,919, which claims priority from U.S. ProvisionalApplication No. 60/558,852, filed Apr. 3, 2004; all of which are herebyincorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an improved system for deliveringpropane or other consumable liquid to and monitoring liquid levels inremotely located storage tanks.

BACKGROUND AND SUMMARY OF THE INVENTION

Propane is a gas, a derivative of natural gas and petroleum. It is oneof the many fossil fuels that are included in the liquefied petroleum(LP) gas family. Because propane is the type of LP-gas most commonlyused in the United States, propane and LP-gas are often usedsynonymously.

Under normal atmospheric pressure and temperature, propane is a gas.Under moderate pressure and/or lower temperatures, however, propanechanges into a liquid. Because Propane takes up much less space in itsliquid form, it is easily stored as a liquid in pressurized tanks. Whenpropane vapor (gas) is drawn from a tank, some of the liquid in the tankinstantly vaporizes to replace the vapor that was removed.

Homes and businesses use about one-third of the propane consumed in theU.S. Propane is used mostly in homes in rural areas that do not havenatural gas service. More than 20 million households use propane to meetsome of their energy needs, while 16 million households use propane astheir main heating source. Homes that use propane as a main energysource usually have a large propane tank outside of the house thatstores propane under pressure as a liquid.

Because home space heating is a primary use of propane, demand is muchhigher during the winter months. Residential users of propane typicallyhave a 250-500 gallon tank installed by a local propane dealer andaccessible to delivery trucks for refilling. Depending on the climate, atypical residential tank is filled three to four times per year. Aresidential tank is usually owned by the propane dealer and rented tothe residential customer for an annual fee.

Propane dealers typically operate out of bulk storage plants thatinclude one to two 30,000 gallon storage tanks. A single dealer willusually be able to effectively service a 35 mile radius around theplant, though in less populated regions a much larger service area maybe necessary to achieve sufficient volume. Propane is delivered tocustomers by bulk delivery trucks or “bobtails” which typically holdfrom 1,800 to 3,000 gallons of propane. Customer tanks usually make upthe largest portion of a dealer's assets.

Obviously, different size tanks and different usage rates for customersover a large area can make it very challenging for a dealer to keep allof his customers' tanks filled. The quantity of liquid propane storedand remaining on customer propane tanks needs to be measured frequentlyso that the propane dealer can manage his own inventory of bulk propane,efficiently schedule deliveries, and most importantly keep his customerssupplied with propane. There are also significant safety concernsassociated with propane tank levels since empty or overfilled tanks canbe very dangerous. Further, costs associated with delivery, includingwages for delivery personnel and vehicle operation and fuel costs, are asignificant portion of a dealer's operating expenses. For this reason,dealers must try to maximize the ratio of gallons of delivered propaneper mile traveled by delivery vehicles in order to lower delivery costs.

Traditionally, the standard practice was for propane dealers toperiodically visit each tank and visually read a gauge located on thetank in order to determine whether the tank needed refilling. If thetank level was low, it would be refilled; if not, the delivery truck hadessentially wasted a trip. As could be expected, this highly inefficientpractice contributed to higher costs, both for the dealer and thecustomers.

For this reason, a number of forecasting methods were developed to givedealers a better idea of how much propane a customer was using and whenmore should be delivered. Since propane is primarily used as a heatingfuel, the typical forecasting method involved factoring temperature andhistoric customer usage rates. A Degree Day is a unit used to measurehow cold it has been over a 24-hour period. The base temperature forDegree-day calculations is 65 degrees. The actual temperature iscompared to the 65° base temperature and if the temperature is lower,the difference is the number of Degree-days for that day. For example,if the average temperature for a 24-hour period was 60°, that would be5° less than the base temperature of 65°, so we would have 5 Degree-daysfor that 24-hour period. Another concept, referred to as the K-factor,is used to get an idea of the propane usage rate for a customer. Thecustomer's K-factor is the number of Degree-days that it takes for agiven customer (or burner(s) associated with a given tank) to use onegallon of propane.

From these two measurements, a dealer could get a better idea as to whenmore propane should be delivered. For example, a customer with a275-gallon propane tank with a historic K-factor of 5 could be expectedto go 1375 Degree-days before the tank is empty. However, since an emptytank is a dangerous condition (plus it means the customer is out offuel) delivery will need to be made before the 1375 Degree-days haveelapsed. Further, these types of forecasting methods cannot account forunexpected periods of higher or lower than normal propane usage. Sincethis kind of forecasting is merely an estimate, a substantial margin oferror must be built into the delivery schedule. This results in moredeliveries of lower amounts of propane and consequently higher dealerdelivery costs.

For many years, various optimal vehicle routing computer programs havebeen available to minimize the mileage and travel time associated withmaking desired deliveries using vehicles with known capacities. All suchmethods in the prior art, however, necessarily depend upon variousmethods of forecasting a customer's propane usage since the lastdelivery and, as discussed above, such forecasting methods are nevercompletely reliable.

More recently, remote monitoring systems have been used to allow remotetransmission of data relating to the level of the liquid gas containedin customer tanks. This allows for the delivery of fuel or other fluidsto the storage tank on an “as-needed” basis. Such monitoring systems aretypically more accurate than forecasting systems and increase theefficiencies of the propane supplier.

Storage tank monitoring systems currently in use typically include afloat sensor within a storage tank that measures the level of fluid andthe temperature within the storage tank. For remote monitoring systems,data from the sensor is transmitted through some type of communicationnetwork to a data processing unit or display device. Typically, the dataprocessing unit is a computer that decodes and stores the data usingspecialized software. The information received by the data processingunit provides for the monitoring of each specific storage tankindividually.

One remote monitoring system known in the prior art makes use of RFbroadcasting to communicate data from the sensor to the data processingunit. Such systems are relatively inexpensive, however, they have verylimited range. The data processing unit would typically be mounted in adelivery truck which would have to be in the vicinity of the customer'stank for the level to be reported.

Another prior art system uses a modem and ordinary telephone lines tocommunicate data from the sensor to the data processing unit. Typically,such a system will use the modem to call in and signal the dataprocessing unit when the propane in a tank reaches a pre-determinedlevel. The customer's phone line must be free for the system to work.

Other prior art systems used to monitor liquid volume in tanks make useof satellite or cellular communications. However, each of these systemsalso suffers from disadvantages in certain circumstances. For example,many satellite systems require an externally mounted satellite dish withthe proper exposure. Additionally, two-way communication requiresexpensive equipment and installation. Cellular systems are not practicalin certain locations due to a lack of cellular coverage.

No matter which communication scheme is used, the data received from thesensor is often confusing and can require significant time to decode andformat into a useful form. Even then, it is still difficult for a dealerto interpret the data or use the information to optimally organize histrucks and routes. Further, a dealer must be able to access the dataprocessing unit in order to make use of the data, and this typicallyrequires that the dealer be physically in his office in order to monitorhis business. Also, certain tank conditions, such as an over-fill or gasleak, require immediate attention. It is sometime difficult to identifycertain dangerous conditions. For example, data showing rapidly fallingfuel levels could indicate a leak or could simply result from a periodof high fuel usage. For events occurring outside ordinary businesshours, either the dealer must have an employee monitoring the system 24hours a day or else these events will not be corrected until the nextbusiness day.

Propane dealers also face economic challenges arising from the seasonalnature of propane demand. As discussed above, demand for propane is highduring the winter months, but much lower during summer. The propanedealer has a significant investment in tanks, trucks, employees, andinfrastructure, and yet he receives a poor return on this investmentduring periods of low demand.

What is needed is an improved system for monitoring the levels ofpropane or other consumable liquid in remotely located storage tanks andto better coordinate delivery of liquid to those tanks.

SUMMARY OF THE INVENTION

An object of the invention, therefore, is to provide an improvedapparatus and method for monitoring the levels of propane or otherconsumable liquid in remotely located storage tanks and to bettercoordinate delivery of liquid to those tanks. This goal is achievedthrough a novel combination of remote monitoring of customer tanks andan improved method of using the remote monitoring data to identifyout-of-ordinary conditions at remote tanks, optimally schedule purchasesor deliveries, improve safety, and more efficiently operate a propanedealership.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter. It should be appreciated by those skilled in the art thatthe conception and specific embodiments disclosed may be readilyutilized as a basis for modifying or designing other structures forcarrying out the same purposes of the present invention. It should alsobe realized by those skilled in the art that such equivalentconstructions do not depart from the spirit and scope of the inventionas set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a preferred embodiment of a remote propane monitoringsystem according to the present invention where a cellular communicationscheme is employed.

FIG. 2 shows a preferred embodiment of a remote propane monitoringsystem according to the present invention where a satellitecommunication scheme is employed.

FIG. 3 shows a typical prior art liquid storage tank and float gauge.

FIG. 4 shows a preferred embodiment of a monitoring unit for use with acellular communication scheme.

FIG. 5 shows a preferred embodiment of a monitoring unit for use with asatellite modem.

FIG. 6 is a typical delivery schedule screen according to the presentinvention.

FIG. 7 is a typical delivery truck routing screen according to thepresent invention.

FIG. 8 is a daily posted customer tank inventory chart according to thepresent invention.

FIG. 9A is a geographic satellite view of a dealer's customer tanks andtheir current levels.

FIG. 9B is the geographic satellite view of claim 9A zoomed in to showan individual customer.

FIG. 10A shows the exterior of an explosion-proof case according to thepresent invention.

FIG. 10B shows the interior of explosion-proof case according to thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A preferred embodiment of this invention provides a novel system andmethod for monitoring the levels of propane or other consumable liquidin remotely located storage tanks and an improved system to coordinatingthe delivery of a liquid to remotely located storage tanks.

Although much of the following description is directed toward propanestorage and delivery, the present invention could be utilized with anytype of consumable liquid commonly stored in liquid storage tanks,including natural gas or anhydrous ammonia. Hence, the scope of thepresent invention should not be limited to propane storage and delivery.Further, although much of this discussion is directed an economic modelincluding a propane dealer servicing propane tanks located at customersites, the system and methods discussed herein would be equallyapplicable to different economic models, including for example, a largecorporation or other business entity servicing a large number of remotestorage tanks from one or more central storage facilities.

In accordance with another aspect of a preferred embodiment of thepresent invention, an agnostic communication scheme can be used forremote monitoring of liquid gas levels in storage tanks. Thus,communication does not have to be limited to a single communicationplatform. Any known suitable communication scheme can be employed totransmit data, such as cellular, land phone lines, wireless, satellite,cable, etc. Different communication schemes can be employed fordifferent customers or tank locations, depending on which scheme isoptimal for the individual client or location. Selection of an optimalcommunication network can be based upon factors such as location,availability of cellular signal, availability of telephone lines, anddesired equipment investment by customer.

FIG. 1 shows one aspect of a preferred embodiment of a remote propanemonitoring system 100 according to the present invention where acellular communication scheme is employed to transfer data between astorage tank monitoring unit and the central server. Remote propanemonitoring system 100 comprises central processing station 102 whichcommunicates with a plurality of monitoring units 107 located atcustomer sites 106 by way of one or more cellular towers 104.Communication between central server 102 and monitoring units 107 ispreferably two-way communication. As discussed in greater detail below,monitoring units collect data from the propane tank sensor andoptionally from one or more home monitoring sensors 108 and transferfluid level data to the central server 102. Data can then be organizedand processed (as also discussed below) and transferred from centralserver 102 through satellite up-link 128 to satellite 110 and/or throughweb server 124 to the Internet or a suitable intranet. Central server102 can comprise one or more computers at one or more locations.End-user 130 can then access data through a wireless satellite link orthrough the Internet, for example by using a personal computer withInternet access. Central server 102 can also communicate with deliverytrucks 140 by way of cellular towers 104.

FIG. 2 shows another preferred embodiment of a remote propane monitoringsystem 200 according to the present invention where a satellitecommunication scheme is employed to transfer data between a storage tankmonitoring unit and the central server. Remote propane monitoring system200 comprises central server 102, which communicates with a plurality ofmonitoring units 207 located at customer sites 106 by way of satellite210. Monitoring units 207 can communicate with satellite 210 by way of asatellite modem and antenna (not shown). In the embodiment shown in FIG.2 communication is one-way from the monitoring units 207 to thesatellite 210. Even more preferably, however, communication betweenmonitoring units 207 and satellite 210 can be two-way communication. Asdiscussed in greater detail below, monitoring units collect data fromthe propane tank sensor and optionally from one or more home monitoringsensors 108 and transfer fluid level data to the satellite 210. Data isthen transferred to central server 102 by way of satellite up-link 228.Data can then be organized and processed (as also discussed below) andtransferred from central server 102 through web server 224 to theInternet or a suitable intranet. End-user 130 can then access datathrough the Internet or suitable intranet, for example by using apersonal computer with Internet access. Optionally, monitoring units ondelivery trucks 140 can also communicate with the central server 102 byway of the satellite 210 and satellite up-link 228.

Tank levels can be monitored by a number of different mechanisms knownin the prior art. For example, one common type of gauge is known as afloat gauge. As the name suggests, a float gauge has a float that restson the surface of the fluid being measured. The position of the floatwill rise or fall as the level of liquid in the tank is changed.Movement of the float is sensed by a gauge, typically through the use ofa magnetic coupling, to provide an indication, either visual orotherwise, of the fluid level. A typical float gauge and propane tankcombination 300 is shown in FIG. 3. Float assembly 302 is mounted insidetank 304. As illustrated in FIG. 3, the position of float 306 will varywith the liquid levels 308 and 310 in the tank. The float assembly 302represents the attachment mechanism through which the sensor unit of thepresent invention detects the level of the propane inside the tanks.Vertical movement of the float as it follows the level of the liquid isconverted into rotational movement by a pinion 312 which rotates a shaftextending inside tube 314 and turns a master magnet 316. The floatassembly 302 attaches by the float head 318 under a pressure seal. Adial gauge 320 is mounted onto the float head 318.

The dial gauge 320 will preferably comprise a dial chamber with a remotesender that gives a visual indication of tank levels while also sendingan electrical signal to a monitoring unit. This electrical signal servesto give a remote indication of the tank levels.

FIG. 4 shows a preferred embodiment of a local customer monitoring unit400 according to the present invention. Monitoring unit 401 comprises asealed case 403 containing processor 402 and at least one associatedcommunication device 404, such as a cellular modem, line modem orsatellite communication device. For example, FIG. 5 shows a preferredembodiment where the communication device is a satellite modem 518 witha flat array antenna 516. Communication device 404 can be connected toexternal antenna 424. Processor 402 and associated communication device404 are preferably powered by batteries 422 or optional external powersupply 423, and communicate with one or more propane tank sensors 412through I/O port 405. Status and troubleshooting information can bedisplayed externally via LEDs 408.

Processor 402 comprises circuitry for implementing the followingfunctions: receiving data from the one or more propane tank sensors 412;processing the data, and converting it into readable form if necessary;at preselected intervals or times, connecting to the central server (notshown) through the associated communication device 404 and externalantenna 424 to transfer collected data; and determining whetherpredefined conditions have occurred, such as a low liquid level or anoverfill, or whether predefined abnormal or “out of ordinary” eventshave occurred, such as liquid levels dropping too fast (possiblyindicating a leak) or not dropping at all (indicating a possible problemwith the tank sensor). As discussed in greater detail below, processor402 can also include circuitry for receiving and storing data from oneor more temperature sensors and use that data to calculate site-specificDegree-day values for each tank location. Skilled persons will recognizethat said circuitry can be implemented with conventional processorsand/or controllers, integrated circuits, discrete devices, or anycombination of the same.

Processor 402 can communicate with tank level sensor 412 by way of adirect wire connection 418, I/O port 406, and communication bus 405.Processor 402 can communicate with a plurality of additional secondarysensors. For example, data can be collected from one or more homemonitoring sensors 421 capable of detecting Carbon Monoxide, propanegas, or variations in temperature inside the customer's home. Data fromthese types of additional sensors can be transmitted to the centralserver along with data on propane tank levels. Communication betweenmonitoring unit 401 and home monitoring sensors 421 can be through anyappropriate means, including wireless RF, X-10, direct wiring. Referringalso to FIG. 5 and FIG. 10B, in a preferred embodiment, a RF antenna 512and antenna can be built into the circuitry of processor 402.Alternatively, a second I/O port allows for X-10 functionality asdiscussed below.

Preferably case 403 will be sealed to protect the sending unit fromadverse environmental conditions. In the event of mechanical failure,the entire unit can be easily replaced. In a preferred embodiment, themonitoring unit of FIG. 4 will also provide I/O functionality (includingdata ports allowing the monitoring unit to communicate with X-10 devicesor the customer's personal computer). Although any appropriatecommunication device can be used with the present invention, in apreferred embodiment the unit will have a primary communication device,such as a cellular modem, and a backup device, such as a land linemodem.

Monitoring unit 401 can be operated by any appropriate power source,including direct wiring, battery packs, or solar chargers. Depending onthe power source, the communication device can be configured to operatein different modes. Preferably, for example, a monitoring unit that ispowered by a battery pack would be configured so that the communicationdevice, such as a satellite modem, is powered off most of the time inorder to conserve power. Processor 402 would periodically wake up thecommunication device to transmit data or receive incoming commands.

In a preferred embodiment, monitoring unit 401 could collect data andreport to the central server once per day at a particular time, forexample at 3:00 a.m. In the case of cellular transmission, this wouldtypically allow a dealer to negotiate a cheaper cellular rate plan sincemost transmissions will not occur during peak cellular times. Iflandline communication is used, reporting at 3:00 a.m. should limit thepotential interference with the customer's use of the telephone line.Additionally, as discussed above, monitoring unit could be configured toreport immediately if certain types of conditions occur, including forexample, overfilled tanks, greater than expected usage (which couldindicate a leak), low battery, or any other “out of ordinary” condition.

FIG. 5 shows another preferred embodiment of a local customer monitoringunit according to the present invention. Monitoring unit 501 comprises asealed case 403 containing processor 520 and battery power supply 514.Satellite modem 518 and flat array antenna 516 are used to communicatewith one or more remote servers (not shown). Suitable satellitecommunication equipment is available, for example, from AeroAstro, Inc.of Ashburn, Va. RF antenna 512 and transceiver (not shown) are used tocommunicate via wireless RF transmission with one or more homemonitoring and automation units such as, for example, Carbon Monoxide orpropane detectors located inside a customer's home. Data from theseRF-enabled units can be stored and processed by monitoring unit 501. Forexample, data from interior monitors can be used to determine whether anautomatic tank cut-off should be activated, as discussed in greaterdetail below. Data from the RF-enabled units can also be transmitted toa remote central server via satellite modem 518.

In accordance with another aspect of a preferred embodiment of thepresent invention, data can be queued until it is reported. This wouldallow the collection of very detailed data, for example hourly tanklevels, while minimizing connect time. This would also allow thecommunication system to be more tolerant of communication faults sincedata would be stored until a satisfactory communication is established.As discussed in greater detail below, the data collected and transmittedby the monitoring unit can include not only tank level data, but alsodata from home monitoring sensors (i.e., CO detector(s), propanedetector(s), appliances, smoke detector(s), security sensors, etc.) anddata from an on-site Degree-day recorder and history log.

In accordance with another aspect of a preferred embodiment of thepresent invention, data received from the tank sensors can be collectedand organized so that it is easily understood and utilized by thepropane dealer through the implementation of a user interface whichallows the propane dealer to see each customer's current status in agraphical and contextual way. This improves the ability of the propanedealer to analyze and react to data quickly and easily without thenecessity of reviewing voluminous data which is not organized in anoptimum order.

For example, in a preferred embodiment, basic information and historywould be accessible for each customer or each storage tank. Acolor-coded tank inventory can be graphically displayed so that a dealercan see a list of customers and tank levels and at a glance tell thestatus of each customer's tank. FIG. 6 is a typical delivery scheduleaccording to the present invention. This screen shows the deliveryvehicles selected for use and the customers scheduled for delivery. In apreferred embodiment, a program running on the central server makes theselection according to user-defined criteria. An authorized user canoverride the program's selections from this screen. A customer tankinventory is graphically displayed so that fluid levels can be easilyseen. Tanks with sufficient propane levels can be indicated with aselected screen color, for example with icons or graphical shapes of aparticular color. Tanks, which need refilling, can be shown through theuse of a different screen color. Over-filled tanks can be shown throughthe use of a third screen color.

FIG. 7 is a typical delivery truck routing screen according to thepresent invention. Each stop on the scheduled delivery route is shown inorder with the physical address, tank capacity, and scheduled deliveryamount. Estimated time of delivery and distance between stops can alsobe shown.

A daily posted customer tank inventory chart, as illustrated in FIG. 8,will preferably allow the dealer to recognize customer use trends anddetect any anomalies, such as an unauthorized tank fill or pump-out.This chart graphically displays the fluid level in a customer's tankover a defined time period, for example over a four-month period. Thisallows the dealer to immediately identify the refill dates and to see ifthere is any drastic change in usage rates.

In accordance with another aspect of a preferred embodiment of thepresent invention, color-coded data can also be displayed on a map thatshows the location and status of each tank. This would also provide foreasy printing of routes and customer locations for drivers. Datareceived from customer tanks would automatically be used to createcolor-coded liquid level tank information lists accessible by thepropane dealer. Custom color-coded maps showing customer locations oneach delivery route can be accessed via the Internet and displayed to aPC screen and printed by delivery personnel. This allows a dealer tohave a geographic or “satellite” view of all of his customer tanks andcurrent levels and to map delivery routes that most efficiently utilizethe dealer's assets and ensure that customer needs are met. Preferably,maps will be able to show an entire customer base, as shown in FIG. 9A,or zoom in on a particular customer or route, as shown in FIG. 9B.

In accordance with another aspect of a preferred embodiment of thepresent invention, tank sensor data can be used to calculate the mostefficient delivery truck routes. It is desirable to determine how muchpropane to load onto each truck, and what stops to deliver in a costefficient manner. Utilizing relevant information, such as tank leveldata received from customers, information on delivery trucks and sizes,availability of trucks, and delivery location points, an adaptivealgorithm would preferably match the needs of the customer database withthe available delivery trucks and model the most efficient routes foreach available truck. By increasing efficiency, dealers can make moreeconomical use of their equipment and employees and can maximize gallonsper mile and gallons per stop ratios. The modeling could also bepredictive by taking historical propane usage for each tank, weatherconditions, and projected fuel usage into account in determining whichtanks should be refilled along a given delivery route. Historic, DegreeDay, and Julian (Elapsed) Day forecasting can also be taken intoaccount. A preferred embodiment could also include a scheduling systemthat would use the optimum route determination to provide fill tickets(specifying how much propane is to be loaded onto each truck) to thestaff responsible for filling up each truck in the morning and toprovide routing and delivery instructions for each driver.

In accordance with another aspect of a preferred embodiment of thepresent invention, the system can calendar required inspections ofcustomer tanks, homes, and appliances, as required by industrystandards, either after an event, such as an out of gas situation, orafter a proscribed period of time as passed. The volatile nature ofpropane gas creates the potential for serious ramifications to occurshould a leaking pipe or joint develop. Dangerous conditions may alsoexist where appliances or heating units with open flames are exposed touncontrolled fuel. Pressure testing the entire propane system,inspecting the tank, piping, regulator, gauges, connectors, valves,vents, thermostats, pilots, burners and appliance controls on a regularschedule or after an out of ordinary event occurs can significantlyreduce the possibility of loss of life or property damage. The systemwill have the capability to alert the propane dealer and drivers to theneed to perform required testing either on a regular timed basis orafter the occurrence of an out of ordinary event.

In accordance with another aspect of a preferred embodiment of thepresent invention, data (in the form of customer information, tankinventories, or delivery information) can be combined with accountsreceivable information. Customer accounts receivable balances can bedisplayed on a PC screen organized by route, or printed out on thecolor-coded route sheets discussed above. This preferably allows thedealer to arrange for payment before or on delivery or to reconfigurethe delivery route where satisfactory payment arrangements cannot bemade with customer.

One aspect of a preferred embodiment of the present invention isdirected to a Web-based (Internet and Intranet) client-serverapplication that enables dealers to access information relating to themonitoring of their propane tanks and inventories, along withinformation related to additional income producing services as discussedbelow. Data from remote sensors, along with the graphical and contextualorganization of that data as discussed above, would thus preferably beavailable to end-users (for example, the propane dealer) by way of theInternet, or a LAN, WAN, or the like.

The end-user could choose to dedicate a computer monitor or monitors tothe continually updated display of such information. Information may bestored on either the central server, a web server, or the end-userscomputer so that historical patterns and trends can be identified.

Additionally, dealers are preferably able to monitor, via a Web browserinterface and in real-time, any alarms or out-of-ordinary eventsaffecting their customers or business. In a preferred embodiment, alarmnotices—such as a tank overfill notice, tank low level notice, anout-of-ordinary occurrence, or a variance from historic or Degree Daydata and projections—can be posted on the Dealer log-in page. The dealercan also be notified of alarms by pager, text messaging, or email.

In accordance with another aspect of a preferred embodiment of thepresent invention, the use of interactive web-based managed servicessoftware, accessible by a number of dealers through individual passcodeprotected Web-site links, allows for across-the-board system upgradesand enhancements without requiring massive hardware or CD mailings.

In accordance with another aspect of a preferred embodiment of thepresent invention, the system for remote tank monitoring of propanetanks can be combined with other products using similar equipment inorder to provide the propane dealer with additional non-seasonal revenuestreams. As discussed above, propane business is seasonal, with highestdemand occurring during the winter months. Although expensive monitoringequipment, which can include satellite, cellular, and landlinecommunication systems, is used primarily during periods of high demand,the equipment remains at the customer's location throughout the year.Similarly, a propane business will typically require a staff with agreat deal of technical expertise, but that expertise is generally onlyput to use during high demand periods. During the off-season, thesehighly trained employees will typically be used for numerousnon-technical tasks.

According to the present invention, a propane dealer can take advantageof the expertise of his employees and the existing monitoring equipmentinfrastructure to provide additional services to customers. For example,the equipment used for satellite communication of remote tank levels canalso be used to provide a customer with satellite television or Internetservice. The same employees who install and service satellite monitoringsystems will be able to use their technical expertise to install andservice satellite entertainment services.

In a preferred embodiment, wireless RF or X-10 functionality on themonitoring unit allows home monitoring and automation services and datato be transmitted with the same equipment used for tank monitoring (evenwhere satellite equipment is not installed or is not available.) As iswell known to those of ordinary skill in the art, the term X-10 refersto a standardized protocol accepted as an industry standard forcommunication between devices via AC power lines within a singlefacility. X-10 communicates between transmitters and receivers bysending and receiving signals over the AC power line wiring. Thesesignals involve short RF bursts, which represent digital information.This X-10 functionality can be controlled by way of the customer's PC,and can easily be accessed through the Internet. As discussed above, ina preferred embodiment, the monitoring unit will have a built-in RFtransceiver and antenna allowing the processor to interface with homemonitoring sensors or home automation devices, such as X-10 devices.Other types of communication protocols and connections could also beused to connect home monitoring sensors to the monitoring unit,including hard-wired connections. This allows the propane dealer to alsooffer, for a relatively small equipment and training investment, homesecurity and fire monitoring, home automation, and specializedmonitoring which is desirable for propane customers, such as CarbonMonoxide and propane gas monitoring inside the home.

By combining wireless entertainment and RF or X-10 functionality withthe tank monitoring system discussed herein, both monitoring andadditional revenue-producing services preferably benefit from costsavings and increased efficiencies.

In accordance with another aspect of a preferred embodiment of thepresent invention, where more than one type of tank monitoringcommunication scheme could be used, the communication scheme can bematched to additional services desired by the customer, thus creatingadditional efficiencies and cost savings. For example, where thecustomer wishes to purchase satellite television or Internet services,the same satellite equipment could be used to provide the communicationbetween the monitoring sensors and the data server.

In accordance with another aspect of a preferred embodiment of thepresent invention, delivery vehicles and storage tanks could be equippedwith GPS transmitters or transmitter-receivers in order to trackdelivery fleet movements and to monitor the location of tanks. Inconjunction with the routing system discussed above, routes for varioustrucks could be changed in mid-route and the new routes delivered to thevehicles GPS system. Additionally, the GPS system could be combined withan automatic vehicle shut-off system which could be automatically ormanually triggered, for example if the vehicle gets too far off of itsassigned route (indicating that the vehicle has been stolen).

In accordance with another aspect of a preferred embodiment of thepresent invention, a tank monitoring system could be equipped with aninternal Degree-day monitor for each tank location. Sensors couldpreferably be used to continuously or periodically monitor temperaturereadings or other weather conditions at each tank site in order tocalculate elapsed Degree-days for each tank location. Site-specificDegree-day calculations could be used to more accurately predict tanklevels and to more accurately determine whether an out-of-ordinary eventhas occurred. These site-specific calculations could either be performedby the tank monitoring system processor or the data could be transmittedto a central server for processing. Daily and accumulated Degree-days(annual) can be stored either by the tank monitoring unit or by thecentral server. As discussed above, Degree-days have historically beenused to estimate propane (or other fuel) usage. However, the Degree-daymonitoring is typically done only one location, such as the propanedealer's office. In some parts of the country, daily temperaturevariations across a dealer's delivery area can be extreme. Monitoringtemperature at each tank location and using that data to calculatesite-specific Degree-days would be a significant improvement over theprior art.

Site-specific Degree-day and historic fuel levels can be used tocalculate the K-factor for each tank. Further, Degree-day and K-factorcalculations can be updated every time a tank's fluid level is measured.This allows the calculations to better account for periods of unusualtemperatures or usage levels, which in turn allows for improveddetection of out-of-ordinary events such as a stuck tank float gauge, anopen bleed valve, an underground line leak, or any reduction in fuellevel not compatible with a customer's history and current weatherpatterns.

Stored and “real time” Degree-day, K-factor, and usage data for a giventank can also be used to calculate predicted tank levels, using forexample, a predictive algorithm taking into account some or all of thedata collected and stored by the monitoring unit. The predicted tanklevels can be compared to actual tank levels to better determine whetheran out-of-ordinary event has occurred. For example, a relatively minordifference between predicted and actual levels might trigger a customercontact or a service call to check for problems. A major differencebetween predicted and expected levels could trigger a more urgentresponse, such as immediate notification of the fuel dealer and customeror an automatic shut-off of fuel flow as discussed below. Data fromsecondary sensors, such as temperature sensors located in a customer'shouse, along with Degree-day, K-factor, and usage data for nearby orsimilarly situated tanks can also be used to calculate predicted fuellevels or to more accurately detect out-of-ordinary events. Again, thesesite-specific calculations could either be performed by the tankmonitoring system processor or the data could be transmitted to acentral server for processing.

In accordance with another aspect of a preferred embodiment of thepresent invention, the tank monitoring system could be configured toautomatically shut off propane flow from the tank in the event of aleak. A significant propane leak in or near a customer's home can havecatastrophic consequences. Automatic leak detection can be difficult,however. Propane gas detectors have sensors and batteries that wear outand they need to be located near the leak to be effective. Also, manypropane customers do not used gas detectors because of the expense ordifficulty in installation. Rapidly dropping fuel levels could indicatea leak, but could also be the result of sudden high propane usage(sometimes seen, for example, when the weather turns suddenly colder orwhen pool heaters or commercial grain dryers are operated). On-siteDegree-day calculation makes it much easier to determine when a leak ispresent. In the event that tank levels are dropping faster than expectedbased upon on-site Degree-days or if levels are falling faster than apredefined amount, a processor-controlled valve could be used to cut offpropane flow out of the tank. Propane flow could also be shut off if anysecondary monitoring sensor, for example one located inside thecustomer's home, detects the presence of a significant amount of propanegas in the air. Preferably, the shut-off valve could also be activatedif the processor receives a command from the central server, such as ashut-off command from the dealer.

In accordance with another aspect of a preferred embodiment of thepresent invention, site-specific Degree-day data could be used to moreaccurately estimate available storage space in customer's tanks, whichin turn can be used by the dealer to more accurately predict when thedealer will need to replenish his inventory. It can take several daysfor propane to travel through pipelines to reach a dealer. Propaneprices also fluctuate significantly throughout the year so that it isadvantageous for the dealer to buy as much propane as possible duringperiods where the price is low. The more accurately propane usage andavailable storage capacity can be estimated, the more efficiently thedealer can determine when to purchase additional fuel and how much fuelshould be purchased. Accurate information concerning customer tanklevels and predicted usage allows the dealer to better make use ofcustomer storage capacity allowing the dealer to purchase more propanewhen price levels are low. In a preferred embodiment, data concerningpredicted weather conditions can also be combined with the datadiscussed above to predict fuel levels several days into the future.

In accordance with another aspect of a preferred embodiment of thepresent invention, Degree-day data and tank level data can be used toestimate actual fuel levels in tanks that have dropped below 5%. Thefluid level gauge on a typical propane tank only goes down to 5%.However, even when the fluid level drops to zero, there is still avolume of propane gas present in the tank and lines that can oftenprovide several days of fuel for the customer. Also, it is important torefill a tank before it has been emptied of all propane gas because anempty tank can pose a significant safety hazard. Before refilling, anempty tank may have to be purged of all air to get moisture out of thetank. Further, the tank should be pressure tested to make sure there areno leaks. Additionally, all pilot lights fueled by the tank will have tobe re-lit. Typically, a propane delivery driver will not be able torefill an empty tank alone because of the time and additional expertiserequired. Instead, an employee with more specialized training andequipment will have to accompany the driver (increasing costs for thedealer). By using Degree-day data and historic tank level data toextrapolate fuel or vapor levels for nearly empty tanks, a dealer canbetter estimate when a tank will be completely empty. This will allowhim to wait as long as possible before refilling, but also to make surethat the tank is not completely emptied.

In accordance with another aspect of a preferred embodiment of thepresent invention, a pressure gauge can be mounted onto a tank so thatactual pressure data can be monitored by the tank monitoring unit in thesame way that fluid levels are monitored as discussed above.

In accordance with another aspect of a preferred embodiment of thepresent invention, the tank monitoring unit is housed within aprotective case designed so that electrical connection to the monitoringunit takes place within an atmospherically sealed chamber. A typicalelectrical connection or metal-to-metal contact creates a risk of aspark—a potentially hazardous event in the presence of any significantamount of propane gas.

FIG. 10A and FIG. 10B show a protective case 403 in accordance with thepresent invention. Case 403 is preferably sealed with an airtight sealto protect monitoring unit circuitry from adverse environmentalconditions and to isolate any electrical connections within the casefrom the atmosphere surrounding the case to prevent explosion in theevent of a propane leak. Referring also to FIG. 5, wire connection 418is used to carry signals from dial gauge 320 to monitoring unit 501.Wire connection 418 is preferably connected to monitoring unit 501 byway of an explosion-proof electrical connection. When male connector 502is connected to female PCB-mount connector 504 a diaphragm or gasket(not shown) is used to create an airtight seal between the male andfemale connectors before any electrical connection is made so that anyspark produced in completing the connection is isolated from theatmosphere surrounding case 403. Skilled persons will recognize that anair-tight seal around the wire connection could be accomplished in anumber of ways well-known in the prior art, including a flexiblediaphragm, a gasket, a mechanical valve, or any combination thereof.

Because the electrical connections and circuitry within case 403 areisolated from the atmosphere, the case can be mounted directly onto atank containing propane or other flammable fuel. Prior art systemstypically make use of a unit mounted inside the customers home thatcommunicates via wired or wireless communication with only a sendingunit at the tank. By using a self-contained tank monitoring unit thatboth receives the data from the tank, and transmits data to the centralserver, the system is much easier to install, allowing drivers ratherthan service personnel to handle installation or replacement ofdefective units. Also, allowing the entire unit to be safely mounted onthe tank itself provides significant advantages. Access to thecustomer's home is not required so that the customer need not be homewhen the monitoring system is installed. Further, locating themonitoring unit outside on the tank makes it easier for the dealer toretrieve the equipment in the event that a customer does not pay hisbills. In the event of mechanical failure, the entire unit can be easilyreplaced, again without requiring access to the customer's home.Preferably the box is mounted on the tank using a connection method thatdoes not involve metal-to-metal contact such as highly adhesive tapeaffixed to the underside of the unit.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made to the embodiments described herein withoutdeparting from the spirit and scope of the invention as defined by theappended claims. Moreover, the scope of the present application is notintended to be limited to the particular embodiments of the process,machine, manufacture, composition of matter, means, methods and stepsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure of the present invention,processes, machines, manufacture, compositions of matter, means,methods, or steps, presently existing or later to be developed thatperform substantially the same function or achieve substantially thesame result as the corresponding embodiments described herein may beutilized according to the present invention. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.

I claim:
 1. A method of monitoring two or more liquid fuel storage tankscomprising: determining the fluid level in each storage tank by way ofat least one monitoring unit associated with each storage tank andcommunicatively linked with a fluid sensor that provides fluid leveldata indicative of the amount of fluid in the storage tank and with atemperature sensor that provides temperature data indicative of theambient temperature at the storage tank location, said monitoring unitincluding a processor to receive and process the received fluid leveland temperature information; storing said fluid level and temperaturedata for each storage tank; predicting future fluid levels for eachstorage tank based upon at least one of the following: (i) determininghistorical fluid levels for each storage tank over a time period fromstored fluid level information; or (ii) calculating the number ofDegree-Days per day for each tank location using said temperatureinformation.
 2. The method of claim 1 in which predicting future fluidlevels for each storage tank further comprises using projected futureweather conditions.
 3. The method of claim 1 further comprising usingpredicted fuel levels for each storage tank to predict liquid fuelstorage capacity that will be available in each tank in the future. 4.The method of claim 2 further comprising using predicted fuel levels foreach storage tank to predict liquid fuel storage capacity that will beavailable in each tank in the future.
 5. The method of claim 2 furthercomprising: determining an estimated delivery date for an additionalquantity of liquid fuel to be stored in the storage tanks; and usingpredicted liquid fuel storage capacity for each storage tank to predictthe total liquid fuel storage capacity that will be available as of theestimated delivery date.
 6. The method of claim 1 further comprisingcommunicating said fluid level and temperature data from each monitoringunit to at least one central server capable of processing and storingsaid data, said central server remotely located from the storage tanksand communicatively linked with said monitoring units.
 7. The method ofclaim 1 in which predicting future fluid levels for each storage tankcomprises: communicating fluid level and temperature data from eachmonitoring unit to at least one central server capable of processing andstoring said data, said central server remotely located from the storagetanks and communicatively linked with each monitoring units;calculating, by the central server, predicted future fluid levels foreach storage tank based upon the fluid level and temperature data fromeach monitoring unit.
 8. The method of claim 7 in which calculating, bythe central server, predicted future fluid levels for each storage tankfurther comprises using projected future weather conditions.
 9. Themethod of claim 1 in which predicting future fluid levels for eachstorage tank comprises: calculating the number of Degree-Days per dayfor each tank location using stored temperature data; and calculatingthe K-factor for each tank based upon the temperature information andDegree-Day calculation.
 10. The method of claim 6 in which predictingfuture fluid levels for each storage tank further comprises using theDegree-Day and K-factor calculations to determine a predicted liquidfuel storage capacity that will be available in each tank in the future.11. The method of claim 10 further comprising using projected futureweather conditions to determine a predicted liquid fuel storage capacitythat will be available in each tank in the future.
 12. An apparatus formonitoring fluid levels in a fuel storage tank comprising: a fluid levelsensor providing information indicative of the amount of fluid in thestorage tank; a temperature sensor providing temperature informationindicative of the ambient temperature at the storage tank location; amonitoring unit associated with the storage tank and communicativelylinked with the fluid level sensor and the temperature sensor, themonitoring unit including a processor to receive and process thecommunicated data from the fluid level sensor and the temperature sensorand a memory to store processed data; wherein at least one monitoringunit is capable of calculating predicted fluid levels in the storagetank based upon the communicated tank sensor data.
 13. The apparatus ofclaim 12 in which monitoring unit is capable of predicting future fluidlevels for each storage tank based upon at least one of the following:(i) determining historical fluid levels for each storage tank over atime period from stored fluid level information; or (ii) calculating thenumber of Degree-Days per day for each tank location using saidtemperature information.
 14. The apparatus of claim 13 in whichpredicting future fluid levels for each storage tank further comprisesusing projected future weather conditions.
 15. The apparatus of claim 12in which the monitoring unit is capable of determining whether apredefined out-of-ordinary event has occurred by comparing actual fluidlevels to predicted fluid levels.
 16. An apparatus for monitoring fluidlevels in a fuel storage tank comprising: a fluid level sensor providinginformation indicative of the amount of fluid in the storage tank; atemperature sensor providing temperature information indicative of theambient temperature at the storage tank location; a monitoring unitassociated with the storage tank and communicatively linked with thefluid level sensor and the temperature sensor, the monitoring unitincluding a processor to receive and process the communicated data fromthe fluid level sensor and the temperature sensor and a memory to storeprocessed data; at least one central server remotely located from thestorage tank and communicatively linked with said monitoring unit sothat processed fluid level and temperature information is communicatedfrom said monitoring unit to the central server: wherein the centralserver is capable of calculating predicted fluid levels in the storagetank based upon the communicated tank sensor data.
 17. The apparatus ofclaim 16 in which the central server is capable of calculating predictedfluid levels in the storage tank based upon projected future weatherconditions.
 18. The apparatus of claim 16 in which the central server iscapable of calculating predicted fluid levels in the storage tank basedupon: calculating the number of Degree-Days per day for each tanklocation using the communicated tank sensor data; and calculating theK-factor for each tank based upon the communicated tank sensor data andthe Degree-Day calculation.
 19. The apparatus of claim 16 in which thecentral server is capable of using predicted fuel levels for eachstorage tank to predict liquid fuel storage capacity that will beavailable in the storage tank in the future.